The drilling of subterranean wells involves assembling tubular strings, such as casing strings and drill strings, each of which comprises a plurality of heavy, elongated tubular segments extending downwardly from a drilling rig into a wellbore. The tubular string consists of a number of threadedly engaged tubular segments.
Conventionally, workers use a labor-intensive method to couple tubular segments to form a tubular string. This method involves the use of workers, typically a “stabber” and a tong operator. The stabber manually aligns the lower end of a tubular segment with the upper end of the existing tubular string, and the tong operator engages the tongs to rotate the segment, threadedly connecting it to the tubular string. While such a method is effective, it is dangerous, cumbersome and inefficient. Additionally, the tongs require multiple workers for proper engagement of the tubular segment and to couple the tubular segment to the tubular string. Thus, such a method is labour-intensive and therefore costly. Furthermore, using tongs can require the use of scaffolding or other like structures, which endangers workers.
Others have proposed a running tool utilizing a conventional top drive assembly for assembling tubular strings. The running tool includes a manipulator, which engages a tubular segment and raises the tubular segment up into a power assist elevator, which relies on applied energy to hold the tubular segment. The elevator couples to the top drive, which rotates the elevator. Thus, the tubular segment contacts a tubular string and the top drive rotates the tubular segment and threadedly engages it with the tubular string.
While such a tool provides benefits over the more conventional systems used to assemble tubular strings, it also suffers from shortcomings. One such shortcoming is that the tubular segment might be scarred by the elevator gripping dies. Another shortcoming is that a conventional manipulator arm cannot remove single joint tubulars and lay them down on the pipe deck without worker involvement.
Other tools have been proposed to cure these shortcomings. However, such tools are often unable to handle tubulars that are dimensionally non-uniform. When the tubulars being handled are not dimensionally ideal, such as by having a varying wall thickness or imperfect circularity of tube section, the ability of tools to adequately engage the tubulars is decreased.
There are many other circumstances in which it is desirable to handle other tubular objects. Indeed, the general handling of large pipe sections can be problematic, and a convenient tool for grabbing and loading pipes is desirable. Indeed, very large pipe sections (with a weight in the order of 6000 kN) are frequently provided with lifting and handling handles, but these generally require personnel to ensure appropriate hook up and disconnect. It would be desirable if a pipe could be provided with a simple mechanism for safe connection and disconnection of a lifting device that did not require human intervention at the site of connection. Of course, much smaller pipe sections might be provided with such lifting arrangements.
Floor slips are employed on production sites to hold casings and drill pipes being lowered into a well while a new length is connected to the top of the pipe or casing being held. An appropriate design of holder that did not need to open to allow flanges and the like on the casings and drill pipes to navigate through the floor slip, as well as not requiring human intervention in the immediate vicinity of the floor slip during holding and release operations, would be desirable.
Emergency disconnect packages are employed to connect rigid risers from subsea installations to surface vessels. Such vessels generally dynamically hold position above a riser but adverse weather conditions and sometimes an inability to maintain position require the possibility of an emergency disconnection from the riser. A device capable performing such function is desirable.